> Which of the following types of clouds is the highest in the atmosphere, oftenappearing wispy and thin?And the answer: cirrus clouds. Often seen during fair weather, cirrus clouds are long and wispy, almost likestrands of hair, and they sit very high in the sky. Due to their high altitude,cirrus clouds are made entirely of ice crystals. Photo credit: PiccoloNamek [https://en.wikipedia.org/wiki/User:PiccoloNamek].Youmay better recognize these clouds in a gorgeous sunset or on a windy day— cirrusclouds are the highest cloud layer in the atmosphere and tend to be mostreflective of its conditions. These delicate clouds tend to be the whitest inthe sky, and their wisps can appear almost silky or tufty. Forming from theascent of dry air, cirrus clouds freeze the water vapor in the air into ice.These ice crystals are responsible for the clouds' bright-white reflectivenature, as well as the delicate shapes that these clouds can take on.Pink skies at night, sailor's delight! Like the rhyme suggests, cirrus cloudsusually form in advance of a warm front – where the air masses meet at highlevels, the cirrus clouds form to indicate a change in the weather is on theway. These clouds physically can not rain, though they certainly try — they canproduce precipitation, but it never reaches the ground. Instead, itreevaporates, creating virga clouds. Did you know?The recognizable "anvil" that tops a cumulonimbus cloud is actually a cirruscloud! A thunderstorm can pump moisture high into the air, where it forms icecrystals. Cumulonimbus cloud. Image: Aviation Stack Exchange.